The Study of NaCl Transport in Aquatic Animals

Kirschner, Leonard B.

doi:10.1093/icb/10.3.365

Cited by 141 publications

(55 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In these, the current had fallen by an average of 90%. In three of four cases, 3 mM meLys reduced the peak current by 90% or more within 15 DISCUSSION Nature and Source of the Stump Currents. Our main finding is that a current with a peak density of the order of 10-100 MiA/cm2 is driven out of the end of the newt's forelimb stump for about a week after amputation.…”

Section: Resultsmentioning

confidence: 81%

Bioelectricity and regeneration: large currents leave the stumps of regenerating newt limbs.

Borgens¹,

Vanable²,

Jaffe³

1977

Proc. Natl. Acad. Sci. U.S.A.

158

View full text Add to dashboard Cite

Electrical currents near regenerating newt limbs were measured with a recently developed vibrating probe.Steady currents with local surface densities of 10 to 100 MA/cm2 or more leave the end of the stump during the first 5-10 days after amputation and are balanced by currents with densities of only 1-3 jA/cm2 that enter the intact skin around the stump. They are immediately dependent upn the entry of sodium ions into this skin and are therefore inferred to be skin-driven. The outward currents are comparable in direction, density, duration, and position to artificially imposed currents previously found sufficient to induce significant regeneration of amputated adult frog limbs. This comparison suggests that the endogenous stump currents play some causal role in initiating regeneration. We have recently demonstrated that anuran limb regeneration can be initiated by driving a small steady current through the stump. The effective stimulus is truly electrical (i.e., the effect is not mediated by electrode products). Current must be pulled out of the stump to induce regeneration, whereas inward current actually induces degeneration (1). Many other stimuli are known to induce a measure of regeneration in adult anurans (2, 3). The critical question is whether a comparable electrical component is part of a natural control system. As a first step in answering this question, we ask whether normally regenerating amphibian stumps generate comparable currents after amputation.An old and nearly forgotten paper of Monroy's indicates that endogenous currents do, indeed, leave the regenerating amphibian stump surface (4). Monroy used a relatively low-resistance galvanometer to make these measurements. Hence, as will be discussed below, it is possible to estimate the size of these currents. Two subsequent studies have yielded somewhat contradictory results (5-7). However, both Becker and the Roses used instruments with very high resistance, so the resistance between the points of measurement was essentially the resistance along the skin surface. Because this was not measured, the size of the currents responsible for the measured voltages cannot be inferred.We have therefore reinvestigated the stump currents in amputated and regenerating newt limbs, using the recently developed ultrasensitive vibrating probe (8). With it, one can directly measure the pattern of current densities entering or leaving a biological source immersed in its natural aqueous medium. Furthermore, the probe is placed at a sufficient distance from the animal as to practically avoid disturbing it. The probe is vibrated between two external points and registers the minute voltage difference generated by any current that may travel between these two points. The only accessory measurement needed to infer the current density is the resistivity of the medium. Use of the vibrating probe allows one to measure exThe costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertis...

show abstract

Section: Resultsmentioning

confidence: 81%

Bioelectricity and regeneration: large currents leave the stumps of regenerating newt limbs.

Borgens¹,

Vanable²,

Jaffe³

1977

Proc. Natl. Acad. Sci. U.S.A.

158

View full text Add to dashboard Cite

show abstract

“…NH 4 + ) permeability through the tight junctions of the gills in SW teleosts (Evans et al, 1989;Evans et al, 2005). However, Wilson and Taylor (Wilson and Taylor, 1992) (Kirschner, 1970) but rather just the NH 4 + concentration gradient. In the current investigation, we have performed a nose-to-nose comparison of rainbow trout exposed to the same HEA level in FW versus SW.…”

Section: Introductionmentioning

confidence: 99%

A nose-to-nose comparison of the physiological and molecular responses of rainbow trout to high environmental ammonia in seawater versus freshwater

Wood

Nawata

2011

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARY Steelhead rainbow trout acclimated to either freshwater (FW) or seawater (SW) were exposed to high environmental ammonia (HEA, 1000 μmol l–1 NH4HCO3, pH 7.8–8.0) for 24 h. SW trout restored ammonia excretion more rapidly (3–6 h versus 9–12 h in FW), despite higher production rates and lower plasma pH. Plasma total ammonia levels stabilized at comparable levels below the external HEA concentration, and blood acid–base disturbances were small at both salinities. The electrochemical gradients for NH4+ entry (FNH4+) were the same in the two salinities, but only because FW trout allowed their transepithelial potential to rise by ∼15 mV during HEA exposure. Elevation of plasma [cortisol] during HEA exposure was more prolonged in SW fish. Plasma [glucose] increased in SW, but decreased in FW trout. Plasma [urea-N] also decreased in FW, in concert with elevated urea transporter (UT) mRNA expression in the gills. Of 13 branchial transporters, baseline mRNA expression levels were higher for Rhcg1, NHE2, NKCC1a and UT, and lower for NBC1 and NKA-α1a in SW trout, whereas NKA-α1b, NHE3, CA2, H+-ATPase, Rhag, Rhbg and Rhcg2 did not differ. Of the Rh glycoprotein mRNAs responding to HEA, Rhcg2 was greatly upregulated in both FW and SW, Rhag decreased only in SW and Rhcg1 decreased only in FW. H+-ATPase mRNA increased in FW whereas NHE2 mRNA increased in SW; NHE3 did not respond, and V-type H+-ATPase activity declined in SW during HEA exposure. Branchial Na+,K+-ATPase activity was much higher in SW gills, but could not be activated by NH4+. Overall, the more effective response of SW trout was explained by differences in physical chemistry between SW and FW, which greatly reduced the plasma NH3 tension gradient for NH3 entry, as well as by the higher [Na+] in SW, which favoured Na+-coupled excretion mechanisms. At a molecular level, responses in SW trout showed subtle differences from those in FW trout, but were very different than in the SW pufferfish. Upregulation of Rhcg2 appears to play a key role in the response to HEA in both FW and SW trout, and NH4+ does not appear to move through Na+,K+-ATPase.

show abstract

“…Paradoxically, by changing the P Cl /P Na ratio, hypoxia may actually help Na + balance in FW, although from this analysis, we have no way of knowing whether hypoxia affects active Na + uptake, which is electroneutral in FW fish (e.g. Kirschner, 1970;Potts, 1984).…”

Section: Resultsmentioning

confidence: 98%

“…The GHK equation was solved for P Cl /P Na ( permeability ratio) under various treatments. The net electrochemical gradient on Na + was calculated as the difference between the Nernst potential and the TEP, signs considered (Kirschner, 1970). Data are shown as means±1 s.e.m.…”

Section: Methodsmentioning

confidence: 99%

“…The usual interpretation is that these effects result exclusively from changes in gill permeability. However, at least for ions, branchial permeability is only one of the three factors affecting both passive and active fluxes; the other two are concentration gradient and electrical gradient, which together dictate the electrochemical gradient on an electrolyte (Kirschner, 1970). However, the electrical gradient is often overlooked.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electrical aspects of the osmorespiratory compromise: TEP responses to hypoxia in the euryhaline killifish (Fundulus heteroclitus) in fresh water and sea water

Wood

Grosell

2015

Journal of Experimental Biology

View full text Add to dashboard Cite

The osmorespiratory compromise, the trade-off between the requirements for respiratory and ionoregulatory homeostasis at the gills, becomes more intense during environmental hypoxia. One aspect that has been previously overlooked is possible change in transepithelial potential (TEP) caused by hypoxia, which will influence branchial ionic fluxes. Using the euryhaline killifish, we show that acute hypoxia reduces the TEP across the gills by approximately 10 mV in animals acclimated to both freshwater (FW) and seawater (SW), with a higher P O2 threshold in the former. TEP becomes negative in FW, and less positive in SW. The effects are immediate, stable for at least 3 h, and reverse immediately upon return to normoxia. Hypoxia also blocks the normal increase in TEP that occurs upon transfer from FW to SW, but does not reduce the fall in TEP that occurs with transfer in the opposite direction. These effects may be beneficial in FW but not in SW.

show abstract

The Study of NaCl Transport in Aquatic Animals

Cited by 141 publications

References 29 publications

Bioelectricity and regeneration: large currents leave the stumps of regenerating newt limbs.

Bioelectricity and regeneration: large currents leave the stumps of regenerating newt limbs.

A nose-to-nose comparison of the physiological and molecular responses of rainbow trout to high environmental ammonia in seawater versus freshwater

Electrical aspects of the osmorespiratory compromise: TEP responses to hypoxia in the euryhaline killifish (Fundulus heteroclitus) in fresh water and sea water

Contact Info

Product

Resources

About